Cardiovascular diseases continue to be an ongoing problem, particularly in an advanced society. Particularly serious is the progressive blockage of a blood vessel by the collection or deposit of materials such as arteriosclerotic plaque and thrombosis. It has been estimated that every year more than one half million Americans die from coronary disease. Another 3.5 million are believed to suffer some degree of incapacitation because of coronary disease.
Various devices and methods have been developed in the past in an attempt to deal with the problems of cardiovascular diseases. One method has been to physically force a blood vessel open. A balloon is positioned within a plaque constricted part of a blood vessel and inflated with the hope that the plaque will be compressed within the walls of the blood vessel and the vessel widened. This process, however, has only met with limited success and is only applicable to certain cases. Various tissue collecting devices have in the past been inserted into lumens to either remove material causing constrictions, or to collect material for biopsy. Other devices have included laser light carrying fibers to direct laser irradiation into the lumen.
All of these devices have their various shortcomings. One common shortcoming is that it is difficult to view a site within a blood vessel while blood is present. To facilitate viewing, it is necessary to occlude the blood flow and flush the blood vessel with a clear fluid such as saline. Even before the flow is fully occluded, the presence of such a device in a blood vessel alone can reduce the blood flow enough to have a detrimental effect upon tissue downstream of the device.
While occluding the blood flow can have little detrimental effect in areas of the body having an extensive cross network of blood vessels (i.e. anastomoses) which otherwise supply the tissue downstream, other areas of the body have few anastomoses. One area of the body having few anastomoses between larger arteries is the vascular network surrounding the heart.
The occlusion of a coronary artery stops the flow of blood and deprives the heart tissue of oxygen downstream of the occlusion. After about fifteen seconds, the cardiac muscle downstream of the occlusion begins to suffer damage and eventually dies. Such an occlusion in nature is known as a myocardial infarction and, if one of the larger coronary arteries is blocked, there can be immediate death.
The prior devices and methods cannot be used in such tissue where the blood flow must be stopped or occluded for any significant length of time. Accordingly, it would be desirable to provide a method which avoids the shortcomings of the prior art and provides an effective means for performing a medical procedure within a blood vessel while providing an adequate oxygen supply to the surrounding tissue. The present invention meets this desire.